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5-Hydroxy-5α-cholest-8-en-3β-yl acetate (8) (prepared in 6 steps starting from 7-dehydrocholesteryl acetate (1) was transformed with ruthenium tetroxide to 5-hydroxy-8,9-dioxo-8,9-seco-5α-cholestan-3β-yl acetate (9). Treatment of the latter 8,9-seco-5-hydroxy derivative with lead tetraacetate (LTA) or mercuric oxide/iodine reagent (HgO/I2) resulted, instead of the expected oxidative β-fragmentation of its C(5)-C(10) bond, in the competing non-regio and non-stereoselective acetoxylation of the α-positions next to the 8- and 9-oxo functions (with LTA), and in the ≈ 82% recovery of the starting material (with HgO/I2). The results are discussed in terms of the strong hydrogen bonding which exists between the 5α-hydroxyl and the 8-oxo group.

In this paper is described a synthetic pathway to the modified 5, 10:8, 14-bisfragmentation cholestene derivatives 10, 11 and 12, which involves introduction of the Δ8(14)-double bond and 5α-hydroxyl group in the cholestane molecule and subsequent cleavage of the olefinic C(8)-C(14) bond (with ruthenium tetroxide) and C(5)-C(10) bond (with mercuric oxide/iodine or lead tetracetate/iodine).